172 research outputs found
Business objects: the next step in component technology?
Component technology seems to be a promising approach towards more efficient software development by enabling application construction through “plug and play”. However, the middleware supporting this approach is still complicated to use and distracts the attention of the component developer from the application domain to technical implementation issues. Business objects are intended to hide the complexities of middleware approaches and provide an easy to use environment for application developers. We conceptualize business object approaches by presenting a common model and survey some major players in the marketplace. We conclude by identifying implications of business objects on information systems engineering.
GPS displacement dataset for the study of elastic surface mass variations
Quantification of uncertainty in surface mass change signals derived from Global Positioning System (GPS) measurements poses challenges, especially when dealing with large datasets with continental or global coverage. We present a new GPS station displacement dataset that reflects surface mass load signals and their uncertainties. We assess the structure and quantify the uncertainty of vertical land displacement derived from 3045 GPS stations distributed across the continental US. Monthly means of daily positions are available for 15 years. We list the required corrections to isolate surface mass signals in GPS estimates and screen the data using GRACE(-FO) as external validation. Evaluation of GPS time series is a critical step, which identifies (a) corrections that were missed, (b) sites that contain non-elastic signals (e.g., close to aquifers), and (c) sites affected by background modeling errors (e.g., errors in the glacial isostatic model). Finally, we quantify uncertainty of GPS vertical displacement estimates through stochastic modeling and quantification of spatially correlated errors. Our aim is to assign weights to GPS estimates of vertical displacements, which will be used in a joint solution with GRACE(-FO). We prescribe white, colored, and spatially correlated noise. To quantify spatially correlated noise, we build on the common mode imaging approach by adding a geophysical constraint (i.e., surface hydrology) to derive an error estimate for the surface mass signal. We study the uncertainty of the GPS displacement time series and find an average noise level between 2 and 3 mm when white noise, flicker noise, and the root mean square (rms) of residuals about a seasonality and trend fit are used to describe uncertainty. Prescribing random walk noise increases the error level such that half of the stations have noise > 4 mm, which is systematic with the noise level derived through modeling of spatially correlated noise. The new dataset is available at https://doi.org/10.5281/zenodo.8184285 (Peidou et al., 2023) and is suitable for use in a future joint solution with GRACE(-FO)-like observations.</p
Physical properties of metal-doped zinc oxide films for surface acoustic wave application
Metal-doped ZnO [MZO] thin films show changes of the following properties by a dopant. First, group III element (Al, In, Ga)-doped ZnO thin films have a high conductivity having an n-type semiconductor characteristic. Second, group I element (Li, Na, K)-doped ZnO thin films have high resistivity due to a dopant that accepts a carrier. The metal-doped ZnO (M = Li, Ag) films were prepared by radio frequency magnetron sputtering on glass substrates with the MZO targets. We investigated on the optical and electrical properties of the as-sputtered MZO films as dependences on the doping contents in the targets. All the MZO films had shown a preferred orientation in the [002] direction. As the quantity and the variety of metal dopants were changed, the crystallinity and the transmittance, as well as optical band gap were changed. The electrical resistivity was also changed with changing metal doping amounts and kinds of dopants. An epitaxial Li-doped ZnO film has a high resistivity and very smooth surface; it will have the most optimum conditions which can be used for the piezoelectric devices
Hybrid crystalline-ITO/metal nanowire mesh transparent electrodes and their application for highly flexible perovskite solar cells
Here, we propose crystalline indium tin oxide/metal nanowire composite electrode (c-ITO/metal NW-GFRHybrimer) films as a robust platform for flexible optoelectronic devices. A very thin c-ITO overcoating layer was introduced to the surface-embedded metal nanowire (NW) network. The c-ITO/metal NW-GFRHybrimer films exhibited outstanding mechanical flexibility, excellent optoelectrical properties and thermal/chemical robustness. Highly flexible and efficient metal halide perovskite solar cells were fabricated on the films. The devices on the c-ITO/AgNW- and c-ITO/CuNW-GFRHybrimer films exhibited power conversion efficiency values of 14.15% and 12.95%, respectively. A synergetic combination of the thin c-ITO layer and the metal NW mesh transparent conducting electrode will be beneficial for use in flexible optoelectronic applications
Identification and design principles of low hole effective mass p-type transparent conducting oxides
The development of high-performance transparent conducting oxides is critical to many technologies from transparent electronics to solar cells. Whereas n-type transparent conducting oxides are present in many devices, their p-type counterparts are not largely commercialized, as they exhibit much lower carrier mobilities due to the large hole effective masses of most oxides. Here we conduct a high-throughput computational search on thousands of binary and ternary oxides and identify several highly promising compounds displaying exceptionally low hole effective masses (up to an order of magnitude lower than state-of-the-art p-type transparent conducting oxides), as well as wide band gaps. In addition to the discovery of specific compounds, the chemical rationalization of our findings opens new directions, beyond current Cu-based chemistries, for the design and development of future p-type transparent conducting oxides.United States. Office of Naval Research (Award N00014-11-1-0212
Deposition of Aluminum-Doped ZnO Films by ICP-Assisted Sputtering
Inductively coupled plasma (ICP) assisted DC sputter deposition was used for the deposition of Al-doped ZnO (AZO or ZnO:Al) thin films. With increasing ICP RF power, film properties including deposition rate, crystallinity, transparency, and resistivity were improved. To understand the plasma-surface interaction, several plasma diagnostics were performed. Heat fluxes to the substrate were measured by thermal probes, number densities of sputtered metallic atom species were measured by absorption spectroscopy using hollow cathode lamps (HCL) and light emitting diodes (LEDs), and neutral gas temperatures were measured by external cavity diode laser (ECDL) absorption spectroscopy. As a result, it was revealed that the high-density ICP heated the substrate through a high heat flux to the substrate, resulting in a high-quality film deposition without the need for intentional substrate heating. The heat flux to the substrate was predominantly contributed by the plasma charged species, not by the neutral Ar atoms which were also significantly heated in the ICP. The substrate position where the highest quality films were obtained was found to coincide with the position where the substrate heat flux took the maximum value
Tuning of Electrical and Optical Properties of Highly Conducting and Transparent Ta-Doped TiO2 Polycrystalline Films
We present a detailed study on polycrystalline transparent conducting Ta-doped TiO2 films, obtained by room temperature pulsed laser deposition followed by an annealing treatment at 550°C in vacuum. The effect of Ta as a dopant element and of different synthesis conditions are explored in order to assess the relationship between material structure and functional properties, i.e. electrical conductivity and optical transparency. We show that for the doped samples it is possible to achieve low resistivity (of the order of 5×10-4 Ωcm) coupled with transmittance values exceeding 80% in the visible range, showing the potential of polycrystalline Ta:TiO2 for application as a transparent electrode in novel photovoltaic devices. The presence of trends in the structural (crystalline domain size, anatase cell parameters), electrical (resistivity, charge carrier density and mobility) and optical (transmittance, optical band gap, effective mass) properties as a function of the oxygen background pressures and laser fluence used during the deposition process and of the annealing atmosphere is discussed, and points towards a complex defect chemistry ruling the material behavior. The large mobility values obtained in this work for Ta:TiO2 polycrystalline films (up to 13 cm2V-1s-1) could represent a definitive advantage with respect to the more studied Nb-doped TiO2
Pbca-Type In2O3: the high-pressure post-corundum phase at room temperature
This document is the Accepted Manuscript version of a Published Work that appeared in final form in
Journal of Physical Chemistry C, copyright © American Chemical Society after peer review and technical editing by the publisher.
To access the final edited and published work see http://dx.doi.org/10.1021/jp5061599High-pressure powder X-ray diffraction and Raman scattering measurements in cubic bixbyite-type indium oxide (c-In2O3) have been performed at room temperature. On increasing pressure c-In2O3 undergoes a transition to the Rh2O3-II structure but on decreasing pressure Rh2O3-II-type In2O3 undergoes a transition to a previously unknown phase with Pbca space group which is isostructural to Rh2O3-III. On further decrease of pressure, we observed a phase transition to the metastable corundum-type In2O3 near room conditions. Recompression of the metastable corundum-type In2O3 at room temperature leads to a transition to the Rh2O3-III phase, thus showing that the Rh2O3-III phase is the post-corundum phase at room temperature. Our results are supported by theoretical ab initio calculations. Furthermore, they show that the Rh2O3-III phase could be present in other sesquioxides, thus prompting to a revision of the pressure-temperature phase diagrams of sesquioxidesFinancial support by the Spanish MEC under Grant No. MAT2010-21270-C04-01/03/04, MAT2013-46649-C4-1/2/3-P, by MALTA Consolider Ingenio 2010 project (CSD2007-00045) and by Generalitat Valenciana (GVA-ACOMP-2013-012). Red Espanola de Supercomputacion (RES) and ALBA Synchrotron Light Source are also acknowledged. B.G.-D. and J.A.S. acknowledge financial support through the FPI program and Juan de la Cierva fellowship, respectively. We also thank J. L. Jorda for fruitful discussions. A.L.J.P. acknowledges financial support through Brazilian CNPq. A.S. expresses thanks to FEDER Grant UNLV10-3E-1253 for financial support.García-Domene, B.; Sans Tresserras, JÁ.; Gomis, O.; Manjón Herrera, FJ.; Ortiz, HM.; Errandonea, D.; Santamaría Pérez, D.... (2014). Pbca-Type In2O3: the high-pressure post-corundum phase at room temperature. Journal of Physical Chemistry C. 118(35):20545-20552. https://doi.org/10.1021/jp5061599S20545205521183
- …